US1643998A - Method of making coils - Google Patents

Description

Oct. 4,1927. 1,643,998

B. R. SCOTT METHOD OF MAKING COILS Original Filed Feb. 19, 1926 Fig. 2-

INVENTOR .Beverlc zy Rand 1 12 Scott,

" ATTORNEY I Patented Oct. 4,1927.

UNITED STATES BEVERLEY RANDOLPH SCOTT, OF WOODLYNNE, NEW JERSEY, ASSIGN OR TO THE PATENT OFFICE} HARLUND MANUFACTURING COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

mn'rn'on or MAKING coins.

Original application filed February 19, 1926, Serial No. 89,292. Dividedand this application filed July 29,

1927. Serial No. 209,276. 1

My invention relates particularly to wire coils used for various purposes such as elec-' tric inductances. I

One object is to providea coil of high inductance value and low dielectric loss, a relatively low resistance and small distributed capacity.

Another object is to provide a coil which can be readily handled and mounted.

Another object is to provide a coil having permanent and uniform characteristics. I I have solved the problem by the simple ex edient of winding a coil upon a very thm layer of dielectric material such as celluloid to which it is permanently anchored by surface adhesion. The method of manufacture which'will be hereinafter described is inexpensive and makes it possible to permanently maintain any desired spacing of '20 the various turns.

Fig. 1 is a side View of a coil made according to my invention.

Fig. 2 is an end view of the same.

Fig. 3 is a perspective view of a mandrel showing one method of applying the dielec-- tric.

Figs. 4 and 5 are' diagrammatic end views of two other arrangements of the support coil of angular cross-section supported on w two stri s of dielectric.

Fi is an enlarged longitudinal see.-

tiona liview showing a fragment of a coil in 3 process ofmanufacture.

Fig. 8 is a similar sectional view showing the same after the wire has been permanently secured-in place.

Th foundation 10 of the coil is made up of=.ione-or more strips of a non-conducting andexpending the mandrel.

simple expe vent, ,such as'ethyl-acetate, to the material l along the l ne of overlap, the edges of the the coil I preferably employ a According to the prefer-red methodof of celluloid, say five-thousandths of an inch thick, is wrapped around the mandrel and the edges of the sheet overlapped, as indicated in Fig. 3, and stuck togethei' by the ient of applying a suitable solmanufacture, a very thin foundation sheet sheet being drawn together smoothly and pressed together immediately after the solvent is applied. 1 have found that this operation of cementing the edges together can be greatly facilitated by the use of a sphincter spring 15. This "spring'normally restsin a groove 16 in one end of the mandrel and is run along the surface of the celluloid as soon as the overlapping edges have been moistened with the solvent. Springs 16' hold the mandrel parts yieldingly together.

. Whenthe edges of the sheet have been united on the mandrel the mandrel is expanded in the usual manner by sim ly drivmg the shaft longitudinally. This places the celluloid tube under tension and holds it smooth. V -The mandrel is then placed in a Winding machine and the wire wound on it under tension. This tension should remain sub stantially constant throughout the windin operation and the feeding of the wire .shoul of course be at the proper rate to laythe wire with the desired spacing between adjacent turns;

' When the coil has been wound, a suitable solvent, such as ethyl-acetate is appliedto the foundation between the adjacent turns of the wire, for instance, by means of a brush. Thissolvent also penetrates the insulation \of the wire and immediately softens the surface of the foundation adjacent the wire.

The coil being under tension, as before described, of course tends to contractin diameter and its inner surface thus sinks slightly in to the softened surface of the celluloid or theflike. "The change in condition before and after the application of the solvent is shownby the difference between therelative The shaft mey be retracted andfthe mandrel contracted and withdrawn as soon as the material .has substantially which requires only a few minutes. The finished coil will, however, continue to dry out for some time, the length of time varying with the composition of the material, the nature of the solvent and the amount aplied, as well as the atmospheric conditions. n drying out the coil shrinks lengthwise,

sometimes as much as 10%. I

\ The coil may be wound at any length desired for special purposes. The method of manufacture lends itself particularly to the production of long tubes which/can be very readily cut up into such lengths as may be desired which is much cheaper than 'the winding of small individual coils.

In the manufacture of vthese tubes, particularly in small diameters, there is sometimes a tendency for the tube to warp when made as above described, due to the overlap ed joint along one edge. This can be rea ily avoided, however, by using two strips, such as 20 and 21, as shown in Fig. 4, so that there will be oppositely disposed joints which will offset each other in the shrinking rocess.

It shoul shown for instance in Fig. HereI have shown four strips 23 with spaces 24 between them, which form an open work or skeleton tube. A coil wound in this manner has an added advantage of reducing the dielectric material to a minimum. Such a coil having no overlapped joint has no tendency to warp in drying.

Although the coil is preferably circular in cross-section, it should be understood that certain features of the invention are applicable to coils of other.cross-sections, for instance, in Fig. 6, I have shown a square coil wound on two se arate strips 25 on o posite sides. This would, of course, leave t e portions 26 of the wires on the intermediate sides of the coil spaced apart from each other without sup orts except at the edges of the strips 25. This requires much less of the foundation material.

Coils wound according to my invention may be used for various purposes, such, for instance, as radio frequency variable couplers, antenna couplers, inters'tage couplers, neutrodyne coils, short wave coils, etc. As they are very light in weight and self supporting they can be easily handled and mounted in various ways This is a division from my application #89,292 filed Feb.'19,, 1926, in-which I broadlv claim a coil comprising a helix of conducting wire together with a sheet of insulating material touching and adhering to a surface of the helix throughout substantially the entire extent of the helix, the wire hardened,

also be .understood that a number of foundation strips may be used andthat these strips may be spaced apart as ,making contact with the sheet 'on only a terial on a mandrel, winding insulated wire tightly thereon, then applying a solvent to I the outer surface of the material between the turns of wire, thereby causing the wire to become partially embedded in the material and then allowing'the material to dry.

2. The method of making a coil which comprises winding wire. under tension onto thin celluloid, then applying solvent to the surface ofthe celluloid to soften it and-allow the wire to become partiallyembedded and then allowing the celluloid to dry and the coil to shrink lengthwise. Q

v3. The method of forming a wire coil which comprises forming a tube ofmaterial such as celluloid, applying pressure to the inside of the tube, winding turns of wire tightly on the tube, applying a solvent to the surface of the tube between the turns of wire and then removing the pressure from the tube and allowing thetube to dry.

4. The method of supporting wire which consists in placing insulated wire ona f0un-' dation of celluloid in spacedfapa'rt relation,

applying solvent to the celluloid between the adjacent walls of the wire so as to cause the celluloid to impregnate the insulation and allowing the. celluloid to set and adhere to the insulation.

5. The method of making a helical induc-,

tance coil comprising placingon a'mandrel a band of insulating material having an insulating binding coating on the outer surface thereof, assembling the turns of said coil on said binding surface, hardening said binding surface after said winding is in place and then removing said mandrel after said binder has hardened.

6. The method of supporting wire which comprises layin the wirein spaced relation on a celluloid-1i e foundation, softening the foundation with a solvent such as ethyl acetate between adjacent portions of the wire, allowing the wire to become sli htly embedded in the foundation andthen a low-- ing the solvent to evaporate and the foundation to harden andadhere to the wire.

7.'The method of formin a coil which comprises, first forming a tu e of celluloid-' like material by joining the edges of a sheet of such material, moistenin one edge with a solvent and causin 'the e ges to adhere to each other, then tig tly winding wire on the tube, the adjacent turns of wire being spaced apart from each other, then applyin a volatile solvent to the material between 0 turns so as to soften the material and permit the wire to be slightly embedded in the softened surface of the material and then allowing the solvent to evaporate until the material sets and holds the turns in place.

8. The method of securing together the turns of wire of acoil which consists in roviding a support having an insulating b1nding substance at the outer surface thereof which is hard at ordinary room temperature, arranging a coil on the support, softening the surface of the substance so as to allow the coil to sink slightly into the surface at the points of contact between the coil and the surface, then hardening the binding substance. V 4 I 9. The method of assembling an inductance coil on a support which consists in providing a support aving a surface of celluloid, applying to the celluloid surface insusoft enough adjacent the coilto allow the Wire of the coil to sink into the softened part, and subsequently allowing the solvent to evaporate and the celluloid support to set and adhere to a relatively small arc of th wire.

10. The method of forming a coil which comprises forming a tube of material whose surface is capable of being softened, supporting said tube on the interior, stretching the material to hold it smooth, winding a conductor on said tube under tension. softening the surface of the tube immediately adjacent the conductor and allowing the material to harden.

BEVERLEY RANDOLPH scorn.

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